package com.leetcode;

import java.util.Scanner;

/**
 * @author Dennis Li
 * @date 2020/9/2 20:56
 */
public class DifferentCharacter {

    public static void main(String[] args) {
        final Scanner scanner = new Scanner(System.in);

        final String str = scanner.next();

        final int[] counts = new int[128];

        int count = 0;

        for (int i = 0; i < str.length(); i++) {
            counts[str.charAt(i)]++;
        }

        for (int i = 0; i < 128; i++) {
            if(counts[i] != 0)
                count++;
        }

        System.out.println(count);
    }

}
